In certain magnetic recording applications, very high data rates are necessary. To accommodate these high data rates, it is customary to employ a rotating member or head carrier on which one or more read/write heads are mounted. The member is rotated so that the heads it carries sweep across the medium, allowing high data rates to be achieved without excessively high medium speed. The usual application is in video recording.
A problem with these rotary heads involves supplying the signals to the heads for writing and receiving the signals for reading. Slip rings are an obvious solution, but the relatively low signal level involved, particularly during reading or playback, results in poor playback accuracy. It is possible to include an on-board amplifier which can increase the power of the signal read back before it is placed on the slip rings. This, however, requires additional slip rings to transmit the power to the on-board amplifier, a multiplexer to switch from one head to another if more than one are employed, and timing control circuitry for the multiplexer.
It is also possible to use a transformer coupling between the rotating head and the remainder of the system, one winding of the transformer rotating with the head carrier. All of these solutions add additional complexity to a system whose price and reliability is not totally satisfactory with present technology. Accordingly, there is strong motivation to reduce the cost and complexity of these assemblies without affecting performance.